Dimetrodon grandis is a species of large sail-backed synapsid in the family Sphenacodontidae. It lived during the Cisuralian and early Guadalupian ages of the early Permain period, between 286 and 270 million years ago. Fossilized remains of this synapsid, one of around a dozen different Dimetrodon species, have been discovered in the American southwest, notably present-day Oklahoma and Texas. The genus name Dimetrodon means “two measures of teeth,” which references its dentition; the teeth in its jaws come in two distinct sizes, which is unusual in a reptile. This is because Dimetrodon and its close kin are not actually reptiles in the strict sense, but instead are related to the ancestors of mammals, which almost universally have multiple different types of teeth. Its species name references its size, as it is the second-largest kind of Dimetrodon known to scientists. It was an apex predator during its own time period, but became extinct around forty million years before the appearance of the first dinosaurs.
Many fossils belonging to this genus have been found in North America since the early years of paleontology. The species Dimetrodon grandis in particular was originally identified by paleontologist Edward Drinker Cope in 1878. Fossils were sent to him from the Red Beds of Texas and Oklahoma. Initially he classified this species as “Clepsydrops gigas,” alongside two other species which he identified as Dimetrodons that year. The neural spine sail puzzled him; he compared it to the basilisk lizard, but understood that it lacked adaptations for climbing in trees, so the sail did not function like the lizard’s. Cope suggested that this was an amphibious animal which could use its sail to steer in water, assuming that otherwise it would get in the way of movement. Others speculated that its sail functioned as camouflage among tall waterside plants.
In 1907, the paleontologist Ermine Cowles Case reclassified “Clepsydrops gigas” into Dimetrodon, but also classified some of its fossils into a new genus “Theropleura grandis.” Case was funded by the Carnegie Institution to work on the taxonomy of Dimetrodon, which had several species which Cope had classified based on very fragmentary remains without proper descriptions. The mantle was eventually taken up by Alfred Romer, who spent several decades studying Dimetrodon taxonomy and clearing up confusion. In 1940, he worked with Llewellyn Ivor Price to fully amend the classification of this animal. This was when Dimetrodon grandis was finally appropriately classified (including both the Dimetrodon “gigas” and “Theropleura grandis” material) and attained its current name, which is still considered valid. The function of its sail was also speculated upon in greater detail, with many paleobiologists suggesting that it may have aided in regulating the animal’s body temperature.
Since then, many other species have been described, with some more recent discoveries even indicating that fossils of this genus can be found outside North America. As of 2022 there were twenty species recognized. Dimetrodon grandis, however, is exclusive to the Red Beds. This species is among the oldest animals yet to become the subject of de-extinction, having been cloned by Biosyn Genetics sometime in the late 2010s. There is controversial evidence that International Genetic Technologies may have cloned this animal from ancient DNA samples prior to Biosyn’s success with it.
Description
Dimetrodon grandis is the second-largest species of Dimetrodon known (surpassed by Dimetrodon angelensis), reaching lengths of 14.76 feet (4.5 meters) and standing around 5.9 feet (1.8 meters) to the top of its neural spine sail. Healthy adults weigh around 498.25 pounds (226 kilograms), though weights up to 661 pounds (300 kilograms) have been reported. It is a quadruped, and while it can move at a modest pace for an animal its size, it is not particularly speedy and built more for short bursts of movement than sustained runs. Dimetrodons are often assumed to be reptiles, but they are actually more closely related to mammals, and they demonstrate a combination of reptilian and mammalian traits. Its gait is sprawling, but it stands with its belly off the ground. The base of its tail is held in the air, but the end of it usually drags along. One of the traits that fully belies its relation to the mammals is its skull. Dimetrodon has a short, laterally compressed skull (the Biosyn specimens show distinctly boxier skulls than usual) with large temporal fenestrae, holes in the skull behind the eye sockets. These features are found in modern mammals, but the early sauropsid reptiles either lack fenestrae or have two pairs of them instead of just one. Some reptiles, such as dinosaurs, evolved similar fenestrae independently.
Dimetrodon‘s teeth are another link to the mammals. As its genus name implies, its teeth come in two different sizes, with larger ones near the front and smaller teeth accompanying them and filling the rear of the jaws. These teeth are caniniform and very finely serrated, allowing them to tear through food but leaving them vulnerable to cracking. Most are wider in the middle, giving them a teardrop-like profile that is unique to Dimetrodon and its closest relatives. Dimetrodon grandis has some of the most specialized teeth for slicing through flesh of any Dimetrodon species, similar to predatory sharks and theropods, since it is an active predator of bigger prey animals. A distinctive tooth gap occurs in the upper jaw where the shape of the jawbone steps to form a noticeable notch. Its nasal cavity is not as advanced as those found in mammals, and can be viewed as a transitional phase between early land animals and the mammals which came later in time. Another transitional feature is the reflected lamina (a ridge in the back of the jawbone), which is ancestral to the tympanic annulus in the mammalian eardrum. Its eyes are much more mammalian than they are reptilian, featuring round pupils, colored irises, and white sclerae; there is also a tapetum lucidum, which reflects light under dim conditions. Many Dimetrodons have blue or amber eyes. While brown tones in the iris are useful in minimizing glare and aiding visibility in bright sunlight, blue iris color is associated with better vision in the dark. The tongue is also fairly mammalian, though its pointed shape is reminiscent of many reptiles.
It has a short but powerful neck, with strong muscles for gripping and shredding meat, which connects to a rather bulky lizard-like body. Dimetrodon‘s lungs are decently strong, and it can hold its breath while walking along lakebeds similar to a hippopotamus. The limbs are stocky and partly sprawled, strong enough to lift its belly off the ground when it moves, and end in five-toed feet. Each toe bears a small claw which helps to grip rocky ground or soil. Its body moves side-to-side as it walks, more like a reptile than a mammal, despite its partly erect gait. Of course, the most recognizable feature of the Dimetrodon is its dorsal sail, a fin-like structure which arises from neural spines that extend upward from the vertebrae. The tallest spine constitutes two-thirds of the animal’s overall height. There are a total of twenty-two such spines in cloned specimens. At the base, each spine is rectangular in cross-section, but changes shape toward the tip to take on a figure-eight cross-section. This reinforces the spine in order to protect it from fracturing. The hypaxial muscles are anchored to the bases of these spines, while the upper parts of the spines support the sail. Surrounding the bone is a layer of tissue called the periosteum which supports blood vessels. These blood vessels are abundant around the spines but less so in the skin of the sail itself; the skin also does not quite cover the entirety of every spine, leaving the tips partly exposed. If any part of the spine is fractured, it will heal over with highly vascularized cortical bone.
Like many other aspects of Dimetrodon‘s anatomy, its skin shows a curious combination of reptilian and mammalian traits. It has mostly smooth skin and may even possess glands like those found in mammals. Dimetrodon is known to bathe in lakes, further suggesting that it has glands in its skin and must wash itself from time to time. However, it also has large, obvious osteoderms which resemble those of crocodilians. The osteoderms are roughly ovoid when viewed from the top, and seem to vary in height from one animal to another. While some have flatter, smoother osteoderms, others may be triangular when viewed from the front or back, extending up to an inch or two away from the body. In all cloned specimens, these osteoderms occur form the neck all the way to the tail-tip, though not on its flanks or belly, and with only small ones on its shoulders and hips. Since fossil skin impressions of Dimetrodon have not yet been found, it is unknown how similar the skin of cloned specimens is to that of their ancestors. The tail of Dimetrodon is unadorned aside from the osteoderms but constitutes a considerable fraction of its total length, with about fifty vertebrae.
Coloration in this animal is mostly a dull greenish-brown hue, with its lower parts and underbelly being marginally lighter in color. Its dorsal ridge is the greenish-gray, rather than greenish-brown, and much of its tail is too. The neural spine sail, however, is very brightly colored. It is red-orange with curved horizontal dark gray stripes, typically three of them, though the number and shading can vary. The color of its sail does not change, suggesting that the red tint is due to pigmentation rather than the animal flushing its sail with blood. The sail plays less of a role in thermoregulation as was once assumed. Dimetrodon is actually believed to be an endotherm, maintaining a stable internal body temperature by means of its own metabolism. It has this trait in common with its mammalian relatives.
Growth
Fossil evidence suggests that, as Dimetrodon grows, the spines supporting its sail are built up with layers of lamellar bone. Immature specimens generally look fairly similar to fully-grown adults aside from size and the number of layers set on each of the spines. The age of a Dimetrodon when it dies can be determined by measuring how much lamellar bone is present in the skeleton.
Other than this, details about its ontogeny are somewhat unclear, including how long it takes to reach adulthood. Specimens cloned by Biosyn Genetics sometime after 2018 were fully grown by late 2022, but they were most likely given growth-boosting supplements to accelerate their maturation process.
Sexual Dimorphism
While the sail of Dimetrodon does become proportionally larger with increases in the animal’s size, the increase in the sail’s surface area is actually much greater than would be necessary if it were only used for thermoregulation. This leads paleontologists to believe that the primary evolutionary driver toward increased sail size is sexual selection, with females favoring males with larger, showier sails. Some scientists have hypothesized that sexual dimorphism can be observed in this animal, since some fossil skeletons have taller sails, thicker bones, and longer skulls with a more pronounced notch in the upper jaw. It has been suggested that these represent males, since these anatomical traits would favor showing off to potential mates and brawling with rival suitors. However, it is not yet scientifically confirmed.
Habitat
Preferred Habitat
During the Permian period, Dimetrodon inhabited vast, low-lying wetlands similar to the Everglades of the Holocene epoch. Its environment was warm and moist, with extensive freshwater marshes and swamps inhabited by a wide range of fish and amphibians which made up its diet. In the modern day, they have been introduced to subtropical coniferous forest environments. They have been discovered to be eutroglophiles, able to establish more or less permanent populations in caves so long as their ecological needs are met. Dimetrodon flourishes anywhere there is shelter and water, so subterranean bodies of water are amenable to them. Because they prefer areas with large bodies of water, they are able to navigate over sandy terrain well, though rocky ground is also suitable.
Muertes Archipelago
There is no evidence to suggest that Dimetrodons have ever inhabited the Muertes Archipelago.
Isla Nublar
The game Jurassic World: Aftermath suggests that at least one breeding female Dimetrodon was present on Isla Nublar as of February 17, 2018. However, this may not be true to the film canon upon which the game is based. No references to this animal having been cloned by International Genetic Technologies have yet come up officially, and even in the game, the identity of a nest of eggs found by the player is known only from the object’s file name in the game data. The nest appears in the North Mount Sibo Genetics Centre.
If this animal was indeed cloned by InGen, none were seen alive by the time of Mount Sibo‘s eruption in June 2018. If it ever lived on Isla Nublar, it is almost certainly extinct there now.
Mantah Corp Island
There is no evidence that this species has ever been housed at the facility on Mantah Corp Island.
Biosyn Genetics Sanctuary
This organism was cloned by Biosyn Genetics at some point during the late 2010s, after the 2018 black-market auction which introduced de-extinction technology outside the scope of InGen projects. It was housed in Biosyn Genetics Sanctuary, a research facility and de-extinct animal sanctuary located in the Dolomite Mountains of Italy. The animals have since taken a liking to the karst ecosystem beneath the mountains that form the boundary of Biosyn Valley, particularly those which are still partly flooded; so long as food and water are supplied to them, they do not really need to leave the caves. They appear to stay underground at least during the night, though they may emerge during the daytime if they want to warm up in the sun or seek sources of food.
During construction of Biosyn’s hyperloop system, a wall in the disused amber mines under a mountain in the southwest was broken and opened up a new passage into the caves where the Dimetrodons lived. Biosyn employees did not notice where this broken cave wall led at first, noticing only strange noises and glimpses of animals in the dark. Eventually, after the disappearance of a worker whose name has not yet been released, extra security requirements were implemented for operations in the mine; by 2022, however, the area was largely abandoned as hyperloop construction was complete. The mines are now part of the Dimetrodons‘ territory. At least three were encountered there during the 2022 Biosyn Valley incident, during which they were confirmed to have fed upon the missing worker. Concept art implies that at least four live there. The amber mines are sealed with an electronic gate at their entrance in the northeastern corner to prevent animals from entering; this means that Dimetrodons cannot exit the mines this way either, and if they need to go above-ground, they must pass through the opening into the caverns and then ascend from there. The animals’ neural implants prevent them from navigating through any cave systems that lead out of the valley.
During the 2022 incident, a wildfire led to animals being herded via their neural implants into emergency containment underneath Biosyn’s headquarters in the northeast. The Dimetrodons were likely included in the remote herding protocol, since it was automated, but if any were left in the caves they would have been safe from the flames here. After the fire was extinguished, the animals returned to their habitats. Compared to surface-dwelling species, the Dimetrodons had little to fear from the fire, since their cave territory contains almost nothing flammable and avoids smoke by being lower in altitude than the surrounding valley floor. It is likely they still flourish in these caves, with the valley now being monitored by the United Nations.
Black market
Through some means or other, Dimetrodon has entered the black market and is traded illegally around the world. At least one specimen is known to have been used as a cockfighting animal in the Amber Clave night market based on Valletta, Malta. While evidence of it was seen during the 2022 Valletta incident, the animal itself was not spotted. Others are most likely in circulation, though the precise number cannot be known for certain; in some cases, the only way to know that these animals are being illegally bred or trafficked in an area is when they turn up in the wild, either having escaped from captivity or been released on purpose. The original black market specimens probably came from Biosyn, though how they made the transfer from company property to black market items has not been determined.
Wild populations
Around 295 million years ago, the first species of Dimetrodon evolved on the continent of Euramerica, which includes landmasses which would eventually split into Europe and North America. The species D. grandis first appeared roughly 286 million years ago; it was one of the largest Dimetrodons, the result of an evolutionary arms race as prey animals continued to evolve larger body sizes that were harder to kill. It lived as the apex predator, common throughout the wetlands and river deltas of Euramerica until around 270 million years ago, when changing environmental conditions caused it to become extinct. As with many long-gone species, the precise changes that led to its extinction cannot be completely known, but not long after the disappearance of Dimetrodon from the fossil record, an event termed Olson’s Extinction took place. This claimed many species, and Dimetrodon may have declined due to early stages of this mass extinction. After the decline of pelycosaurs like Dimetrodon, the therapsids took ecological prominence, setting the stage for the evolution of mammals.
Although Dimetrodon became extinct, its bones were buried in the wetlands where they had once flourished, and over millions of years they became entombed in the sediment and fossilized. Hundreds of millions of years later, scientists discovered that iron structures had allowed non-trivial quantities of DNA molecules to survive though this vast gulf of time, and using advanced genetic engineering techniques they brought Dimetrodon grandis back to life. While efforts were taken not to alter it from its original form, this is an unavoidable result of the de-extinction process, so the modern Dimetrodon has some differences from its ancestor.
The Department of Prehistoric Wildlife is aware of Dimetrodons living in the wild, despite this species having been cloned for research by Biosyn Genetics. Most likely, animals removed from Biosyn’s facilities were sold on the black market and then either escaped or were released deliberately once they grew too large for their owners. While the DPW has not reported any specific locations (the reported animals may have been captured and thus removed from the wild), Dimetrodons have been said to occur in both natural caves and artificial sewer systems, anywhere they can find shelter, food, and water. Should populations establish in the wild permanently, there are a few areas in the world where they might flourish once again. For example, paleoecologists believe that the Everglades have historically approximated the Euramerican wetlands where Dimetrodon first evolved.
Behavior and Ecology
Activity Patterns
Paleontologists originally assumed that the Dimetrodon was a poikilothermic animal, meaning its body temperature was highly variable and dependent upon the surrounding environment. This would make it reliant on the sun to warm up, implying diurnal behaviors. However, as of 2022, scientists instead believe that Dimetrodon and other sphenacodonts were most likely endotherms capable of maintaining a consistent internal body temperature. This would allow it to be active during both day and night.
Observations of cloned specimens in Biosyn Valley yield similar conclusions: the animals can thrive in cave environments where they have minimal sunlight exposure, yet they remain fully capable of moving around, including chasing prey and defending territory. The eye of a Dimetrodon has a tapetum lucidum, which often occurs in nocturnal animals. It is possible they emerge at night to search for food, but they have been seen staying overnight in caves, suggesting that not all of them hunt every night. It is also possible that they could emerge during the day if they want to warm up, conserving energy that would otherwise go toward increasing their body heat in the cool of the caverns.
Diet and Feeding Behavior
This animal is a carnivore, and most of its diet consists of animals that it can find and catch in wetland habitats, such as fish and amphibians. The teeth of D. grandis are the most specialized of all Dimetrodon species toward ripping through meat, the result of millions of years of evolution in tandem with its prey items. As its prey evolved larger body sizes, Dimetrodon followed suit and selected for increasingly effective teeth. This arms race between lineages of predator and prey culminated with this animal, whose jaws are highly efficient at puncturing the flesh of prey items and tearing off chunks of meat which it then swallows whole. With its natural prey including large amphibians and freshwater fish related to modern sharks, Dimetrodon is capable of maintaining its grip on even slippery victims using its teeth. Their teardrop-like conical shape enables the piercing, and fine serrations enable the ripping. It is not fast, but neither were its prey items during the Permian period, so it could make do with ambush attacks and brief chases. Being warm-blooded rather than cold-blooded probably helped it outlast its amphibious prey during pursuit, since it had more energy available, but this biological trait comes at a higher metabolic cost. As of such, both in prehistory and today, Dimetrodon cannot go as long without eating as some reptiles and amphibians can.
Living in the modern day after being brought back from almost three hundred million years of extinction puts Dimetrodon in a difficult position when it comes to finding food. When it first evolved, vertebrate life on land was getting large for the first time, and many of the survival traits we see today had yet to appear. During the hundreds of millions of years it was extinct, countless generations of predator-prey interactions have yielded animals far more advanced than what Dimetrodon evolved to hunt and eat. Gone are the huge lumbering amphibians, and in their place are faster, smarter, and better-defended megafauna. This presents a challenge, one which D. grandis has acclimated to in interesting ways. Researchers in Biosyn Valley, where most of the modern Dimetrodon population lives, have observed the animals favoring cave environments with flooded chambers. They likely capture fish from these waterways, but aside from that, the kinds of animals that live in caves are too small to sustain one Dimetrodon, let alone a population.
However, the caves they inhabit serve a different purpose when it comes to food. Should they find meat on the surface, or manage to kill an animal that is too inattentive, clumsy, or simply unfortunate to avoid these slow predators, they will drag it back into the cave. Dimetrodon territories are often identifiable by caches of skeletal remains as well as carrion, suggesting communal feeding habits. Dung is commonly seen around the entrances to the caves, further suggesting that they all feed in the same place. Its eyes are well-adapted to low light, with traits that suggest it can hunt in the dark effectively, but some Dimetrodons are known to stay underground during the night despite prey being scarce here. This suggests an intriguing possibility: that the Dimetrodons do not all emerge to hunt every night, but instead bring food back to the cave where they all share in the spoils. This would reduce the risk to any one individual animal, while ensuring that all of them remain fed. There is no evidence of infighting among them, at least while food is plentiful, further suggesting that they have no issues sharing food among each other. Animals that stumble into their caves and become disoriented are also easy prey; Dimetrodons have been known to claim human victims in this way.
Social Behavior
Dimetrodon is a modestly social creature that prefers to live in small groups among its own kind. As described above, there is some evidence that they may share food with one another, though the behaviors surrounding this have not been documented. Those that bring home the best food, or largest quantities, are probably valued by the rest of the group. These are relatively simple creatures and probably do not have any kind of division of labor, but it is easy to imagine that the most skilled hunters and foragers are likely to hold authority among their kin.
The bright color of Dimetrodon‘s sail, especially when compared to the relatively dull hue of its body, almost certainly indicates a form of social display. It has been suggested that these animals are sexually dimorphic based on fossil evidence, and if so, the males likely use their sails to show off to potential mates and intimidate rivals. The neural spine sail is a large and obvious feature which is visible from a distance, and to an animal with good color vision, it acts as a beacon that other Dimetrodons can recognize immediately. Paleontologists believe that this sail originally evolved as a visual signal rather than for thermoregulation as was once assumed.
They will converge on threats and appear to work together to drive out intruders from their territory, although they are not intelligent enough to make complex strategies. In the game Jurassic World: Evolution 2, sometimes Dimetrodons will approach others of their kind that are resting and will cuddle up with them, showing affection through physical contact. These feelings may not be reciprocated, however.
Reproduction
The only depiction of Dimetrodon reproduction in a film-adjacent canon is from Jurassic World: Aftermath, in which a nest of eggs is identified in game data as belonging to this animal. The game implies that Dimetrodon builds ground nests out of debris and soil it finds in its environment, and favors sheltered places to lay its eggs similar to where it is known to reside in the film canon proper. The eggs seem to be laid sometime during the rainy season, as they were observed in February. Its eggs are white and oblong, more like those of a reptile than a monotreme mammal such as the platypus or echidna. However, both non-dinosaurian reptiles and monotremes have eggs with leathery shells, so Dimetrodon eggs probably have this same texture. It is unknown at the moment how they choose mates, though the neural spine sail is most likely used in courtship displays, nor is it known how long the eggs are retained in the female’s body or how long they take to hatch. In monotremes, the female carries the eggs for an extended period of time, and they hatch after only a few days once they are laid. The reproductive organs of Dimetrodon have also not been studied. It probably possesses a cloaca, which is seen in egg-laying mammals, but they may have a separate genital tract, or at least the male may possess some form of intromittent organ. The latter is the case in monotremes.
While mammals nourish their young with milk secreted from glands, and while Dimetrodon‘s skin may possess glands similar to those found in mammals, it is believed to have evolved before mammary glands did and therefore is unable to produce milk. If it cares for its young, it more likely provides them with meat until they are able to hunt food for themselves. The maturation process is not well known, though young probably feed on small animals such as insects, gradually choosing larger food items as they get older. As they age, their neural spines become reinforced with layer after layer of lamellar bone, preparing them for the task of supporting a large, vibrant sail of skin.
Communication
Despite its primitive position on the tetrapod evolutionary tree, Dimetrodon has a decently developed social life and uses a few different methods to communicate with its own kind. Perhaps the most important, yet least studied, is the visual signalling that its sail has evolved for. This is the most obvious, vibrant part of its body, easily recognizable when viewed from the side, and appeals to the sense Dimetrodon primarily uses to detect the world around it: its vision. Dimetrodon‘s eyes are very mammalian, so it likely sees a similar range of colors to the more primitive mammal species. Its senses of smell and hearing are less advanced than in mammals, so they are probably not as important.
Dimetrodon also uses vocalizations to communicate. This is not as common, and it tends to be a fairly quiet creature, probably just using simple hisses and grunts to acknowledge others and carry out basic social interactions. When it is agitated, though, it can become alarmingly loud, emitting shrieks, howls, and wails that are unlike any of the noises produced by their reptilian neighbors. Some of these cries can sound eerily like human screams. Cave acoustics carry these cries farther by echoing them along the passageways, ensuring that all the Dimetrodons can hear. They mostly cry out like this when they detect a potential threat, such as an intruding animal, so these sounds most likely serve to alert the other animals to danger within the territory.
Ecological Interactions
In the modern age, Dimetrodon is not the apex predator it was in the Permian, having missed out on hundreds of millions of years of evolution. It is still a carnivore which actively hunts prey, but it must now contend with the existence of other, more specialized predators (both de-extinct and naturally extant). This may be part of the reason why it avoids other animals, keeping to itself in sheltered habitats. In Biosyn Valley, Dimetrodon exploits cave environments where few other large species live. They may face some competition for territory from Baryonyx, which also likes caves and feeds on fish, but this has not been observed directly. Instead, the main animals that they probably encounter in their preferred habitats are small, mainly arthropods and other invertebrates, as well as smaller vertebrate animals such as fish and bats. Fish, at least, constitute an important part of its diet.
Dimetrodon shows adaptations for hunting at night, such as tapeta lucida (layers of tissue in the eyes which aid in night vision, and are responsible for the eyeshine effect). It probably preys on animals that are less adapted to getting around in the dark; however, there are other nocturnal hunters in Biosyn Valley, such as the venomous Dilophosaurus. Most of its relationships to other Biosyn animals are poorly known and it may not interact with all of them. Near the caves where it can be observed, there are large herbivores, most of which are too large for Dimetrodon to consider prey. The largest of these, the sauropod Dreadnoughtus, is frequently accompanied by fish-eating Pteranodons which could compete with Dimetrodon for food. The small theropod Pyroraptor, another reclusive species, is a skilled diver and could probably outperform Dimetrodon in hunting fish. Were these animals to compete, Dimetrodon would have to rely on its bulk to win.
Though it probably gets much of its meat from carrion, there are some animals in the valley that Dimetrodon could manage to kill without much trouble. The Central European red deer (Cervus elaphus hippelaphus) was chosen by Biosyn animal specialists as an ideal prey species for most of the carnivores in the valley, and were a Dimetrodon to successfully ambush one, it would provide a decent amount of meat. There are also the many fish species native to Italian rivers which they could eat, and as juveniles, they could subsist off of insects, reptiles, and amphibians. The entrances to their caves are often littered with dung and the remains of unfinished meals, which would attract scavengers; it is not known whether Dimetrodon tolerates the presence of small detritivorous animals, or if it chases them off. It is moderately aggressive toward animals its own size, which it assumes to be territorial threats. When it discovers an intruder, it will scream and chase until the animal leaves. Should it catch an intruder with its jaws, a Dimetrodon will not hesitate to make a meal of it.
Cultural Significance
Symbolism
Having been discovered in the late nineteenth century, Dimetrodon is firmly a staple in the public’s image of the prehistoric world, sharing the spotlight with animals such as dinosaurs and pterosaurs. Many laypeople assume that it is a reptile from the Mesozoic, if not actually a type of dinosaur; they may be shocked to learn that Dimetrodon is more closely related to humans than it is to dinosaurs, despite being considerably more ancient than either. Educators often reference this genus as an example of common misconceptions that laypeople have in regards to paleontology and taxonomy; it may be difficult to explain to an average person that a bird is a kind of reptile, but Dimetrodon is not. Among people who are a little better informed, the knowledge that Dimetrodon lived and died a full forty million years before the earliest known dinosaurs makes it emblematic of not just the prehistoric, but the truly primeval, a time when four-legged animals were first carving out niches on land.
This animal has been featured in paleoart of all kinds, ranging from professional illustrations to cheap plastic toys, since the very early days of paleontological science. The abundant artwork of Dimetrodon is both a result of and a contributing factor to its fame in the public eye. To people interested in prehistoric life, this creature is a good example of a lineage in transition; it has some features of reptiles, but is visibly similar to mammals, even if its mammalian traits are not especially advanced.
In Captivity
Although there is questionable evidence of International Genetic Technologies cloning and housing this synapsid, the only confirmed cases of Dimetrodons in captivity come from two sources: Biosyn Genetics Sanctuary, and the animals illegally purchased from the black market. Not much is known about the latter, other than that at least one of these creatures was used as a cockfighter in the Amber Clave market in Malta as of 2022. It goes without saying that its treatment is inhumane, and not representative of what this animal would need in order to really thrive. In Biosyn Valley, they are permitted to roam as they choose, with only their neural interface devices restricting them (mainly stopping them from leaving the valley, approaching vehicles, or entering buildings that are in active use). Generally, the Dimetrodons inhabit caves within the mountains ringing the valley, mainly emerging in search of food. They are known to pose a hazard to workers; in the early 2020s, work on the hyperloop system resulted in a wall of the disused amber mines collapsing and forming a passageway into an adjacent cavern which was inhabited by Dimetrodons. This breach was not noticed at first, and was only suspected after maintenance and construction workers reported hearing noises and seeing signs of animal activity. After the disappearance (later confirmed to be a fatality) of one worker, additional safety protocols were implemented to prevent further incidents.
Biosyn’s Dimetrodons are sustained by the natural systems of the valley, with the only outside input being the continuous reintroduction of red deer. To keep these synapsids in a more closed environment, some extra effort would be necessary to maintain their quality of life. These are wetland animals, and at the very least need large bodies of freshwater to drink and hunt from as well as bathe in. Aquatic systems are complex and difficult to maintain, even freshwater ones, presenting a challenge to their keepers. Aisde from this obstacle, Dimetrodon seems fairly manageable for a predatory species and is visually stunning with its neural spine sail, making it a potential draw for visitors should it ever be put on public display.
Science
Many fossils of Dimetrodon grandis have been found over the years, beginning in the late 1870s, so a large amount of information about its biology has been uncovered. Aspects of its ontogeny, diet, metabolism, and ecology are well understood; in fact, the only thing that is still up for debate is the function of its sail, which puzzled Edward Cope when it was first discovered. For a long time, scientists assumed that it evolved primarily for thermoregulation, and that this was an animal with reptile-like traits and thus an ectotherm. However, some species of Dimetrodon as well as its relatives had sails that were disproportionate to their body size. Some had small bodies but larger sails than they would need for warming up or cooling down, or they had the reverse, with large bodies and sails too small to perform these functions. Among the species which did grow larger sails as they achieved larger body size, the increase in proportional size of the sail is much more than would be necessary to provide the same thermoregulatory functions. In fact, the rate at which the size of the sail increases is similar to that of antlers in deer. This has led some scientists to conclude that the sail of Dimetrodon had some functions in common with deer antlers; that is, they were used to show off to potential mates, and that this was probably the reason neural spine sails evolved among the sphenacodonts in the first place.
Dimetrodon displays many anatomical features which it has in common with mammals, such as the temporal fenestrae in its skull, as well as some features which would in later synapsids evolve into features found in mammals today. This makes it a useful example of how the anatomy of more primitive tetrapods became progressively specialized in various different kinds of animals in order to give rise to what is now seen in modern species. It also yields information about the ecosystems that existed during the early Permian period. When it first lived, the continent of Euramerica was in the tropics, and coastal wetlands sprung up around extensive river deltas. It is here that Dimetrodon lived, preying upon primitive sharks and large amphibians. The species Dimetrodon grandis showcases not just how this synapsid became an apex predator, but also how its evolution was a result of an arms race between predators and prey. Earlier species of Dimetrodon fed upon smaller animals, but over time, its prey attained greater body mass, and Dimetrodon evolved to keep up. This species possesses teeth that are exceptionally suited to tearing through the flesh of prey.
The de-extinction of Dimetrodon is also an impressive scientific feat, as it is among the oldest animals yet to be brought back to life. Since it lived before mosquitoes or even the trees that could produce resin which would become amber, the only way to obtain Dimetrodon DNA is by extracting it from fossilized remains that were preserved within the unique iron structures identified by InGen in the early 2000s. This is considered less efficient than amber, so it surely took extensive research for geneticists to successfully revive such an ancient creature. Now that it lives again, questions about its biology can be answered more definitively, and it may also yield new insights into the evolution of early mammals. Since this also has significance in the field of human evolution, it may result in new discoveries related to human anatomy and physiology that could help scientists better understand how our bodies work.
Politics
While there have been reports described to the Department of Prehistoric Wildlife of Dimetrodon in the wild, there are currently no confirmed wild specimens, with all live animals either contained in sanctuaries or held illegally in the black market. While both of these practices have their controversies, none are specifically focused on Dimetrodon, although the rights of de-extinct carnivores are often more contentious than those of other animals. The possibility of Dimetrodon infestation is, at least, one motivator for governments to prioritize proper sewer maintenance.
Currently there is one confirmed human death caused by Dimetrodons, a Biosyn employee whose death was a result of company negligence. Under CEO Lewis Dodgson, his death was covered up and hidden from the public. It was not confirmed until his remains were found by accident during the 2022 Biosyn Valley incident. Safety measures had by that time already been put in place to protect workers from animal attacks in the caves.
Resources
Since it was cloned in the 2010s, de-extinct Dimetrodons have been the subject of biomedical research. They have yet to be tested in a park environment where visitors can view them, though even the fossils of extinct specimens are popular exhibits. Biosyn Genetics Sanctuary houses several of these animals and Biosyn has spent years documenting their genome and physiology in the interest of discovering new biopharmaceuticals, which hold the potential to treat numerous human diseases. Because Dimetrodon is related to the ancestors of mammals, it may be more applicable to human health than most kinds of dinosaurs. This animal is significant in that it is among the first non-archosaurs to be studied extensively, as most de-extinction research before its cloning had been focused on the charismatic dinosaurs and pterosaurs. Only a few other non-archosaurs had been researched in detail prior to Dimetrodon, and most of these (such as Mosasaurus) were still reptiles. Dimetrodon shares its distinction in the history of de-extinction research with the therapsid Lystrosaurus, which also inhabits Biosyn Valley.
A less respectable use of Dimetrodon in the modern day occurs in the black market, where this rare creature is illegally bought and sold for a range of purposes. Most notoriously, its strong jaws and stout build make it a decently capable fighter, and as of 2022 there was at least one of them being entered into matches in the Amber Clave‘s cockfighting pits. Its sail likely also makes it a prized exotic pet due to its stunning appearance. They are also of value when dead; they could be harvested for their hides, meat, and bones. Their skin is an unusual combination of reptilian and mammalian, and their meat is likely similar to that of primitive mammals and therefore a rare and exotic food. Dinosaur bone powder is often traded on the black market, and while Dimetrodon is rather distant from the dinosaurs in evolutionary terms, this is likely a matter of little importance to people who believe that the powdered bones of de-extinct life forms have curative properties.
Safety
As of 2022 there were no active reports of this animal in the wild, but there will always be a chance that it will turn up someplace where people might encounter it, so it is better to be prepared. If you have reason to believe that Dimetrodons are living in your area, the best way to avoid running into them is to know where and when they are most likely to live and hunt. They avoid other animals by sheltering underground, and they have adaptations to nocturnal activity. Even if they are not exclusively nocturnal, they will be much easier to spot during the daytime. Discourage them from taking up residence in sewer systems and other water drainage infrastructure by performing regular proper maintenance, cleaning up debris that might otherwise accumulate and turn the sewer into a nutrient-rich, welcoming environment. If openings to any underground spaces can be barricaded or otherwise closed off, you should do this when they are not in use, especially if they may fill with water. Dimetrodons evolved in wetlands, so they will be attracted to watery environments. The enclosed parts of abandoned buildings may fill with water, so it is pertinent to also support the upkeep or at least monitoring of disused buildings whose basements might flood and become inhabited by animals.
Dimetrodons often leave signs of their presence near the entrances to their nests, such as the bones of past meals, partially-eaten carcasses, and droppings. If you see such evidence, contact your local authorities to locate and remove the animals. If you work in an environment such as a paleo-sanctuary where these animals are a regular part of the local fauna, do not venture into caves or other underground spaces alone. Having more people around will make it easier to hear or spot approaching Dimetrodons. They are usually quiet animals, so bring a flashlight; their eyes are reflective in the dark and so this may be the first way you spot them. Always ensure that you know at least two routes out of any part of a cave, in the event that your escape route is blocked. You can throw objects to distract them briefly, and protective clothing may reduce the injury you take from a bite; focus on protecting your legs, since Dimetrodon is built low to the ground. If you fall, keep it away from your upper body by whatever means you can. If you have followed prior advice and not entered caves by yourself, also be ready to aid your companions should they come under attack. Most able-bodied people can move faster than a Dimetrodon, at least over distance, so do not slow down or stop and exit the cave by the least dangerous route available. If you are in a wetland area, quickly move away from the water, since Dimetrodon excels in aquatic environments. Once in the open and on solid ground, it should be fairly easy to outmaneuver a Dimetrodon. It is a visual predator, so try and get out of its range of sight before you stop to rest. As a last resort to defend yourself, strike at vulnerable spots such as its nose or eyes.
Really, the best way to practice safety with Dimetrodons is proper maintenance of any infrastructure that they might be tempted to live in. Avoid allowing any underground spaces to fall into disuse, and drain floodwater from basements, sewers, tunnels, and other structures. If any of these underground spaces are joined to natural caves, keep these connections blocked off to prevent unwanted entry, and keep artificial entrances to underground spaces closed off when not in use. Dimetrodon is a territorial animal that does not want to be around people, so as long as you keep these areas maintained, well-lit, and frequently visited, they will not be appealing to these creatures and they will seek somewhere else to live.
Behind the Scenes
Before it appeared in the flesh in Jurassic World: Dominion, a diorama of a Dimetrodon appeared in Jurassic World: Fallen Kingdom. The appearance of the live animal seems to have been based on the diorama, which also bears some resemblance to a Dimetrodon that appeared on the cover of the IDW comic book Jurassic Park: Redemption III.
According to game data, the nest of eggs seen in Jurassic World: Aftermath belongs to a Dimetrodon, though the animal itself does not appear in-game. While this implies that InGen cloned Dimetrodons, they are said in the game Jurassic World: Evolution 2 to have been engineered from scratch by Biosyn. The story from either of these games may be soft-canon, or neither, or some combination of both games (for example, InGen cloning Dimetrodon and never announcing it due to the park’s closure, leading to Biosyn believing they had bred it first).
Disambiguation Links
Dimetrodon grandis (L/M)
